Loop hanger for seat belt

ABSTRACT

A loop hanger for a seat belt ( 10 ) which slidably hangs a seat belt webbing (S) is provided with a base member ( 20 ) made of a metal plate and having a slot ( 21 ) through which the seat belt webbing (S) is moved, wherein the slot ( 21 ) is constituted with a long side portion ( 21   a ) extending in a generally horizontal direction and a pair of left and right short side portions ( 21   b ) communicating with left and right end portions of the long side portion ( 21   a ) and extending downwardly, a portion of the base member ( 20 ) surrounded by the long side portion ( 21   a ) and the pair of short side portions ( 21   b ) is curved smoothly from a side of the long side portion ( 21   a ) in a generally C-shaped sectional configuration, and a curved face ( 21   f ) formed by curving the portion of the base member ( 20 ) serves as a portion ( 20   a ) through which the seat belt webbing (S) is turned back. Accordingly, anti-gum up property can be improved largely.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 09/894,664filed Jun. 28, 2001, now U.S. Pat. No. 6,662,426.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a loop hanger for a seat belt whichslidably supports a seat belt webbing (webbing belt) so as to turn overthe seat belt at its intermediate portion, the seat belt being providedsuch that it can be pulled out in an ordinary situation of a vehicle andit can be prevented from being pulled out in an emergency situation ofthe vehicle, for example, like a three-point seat belt system for anautomobile, and a method for manufacturing the same.

2. Description of the Related Art

In recent years, in order to protect an occupant of an automobile at atime of a vehicle collision, a three-point type seat belt which holdsthe beast of an occupant in a manner extending from the waist of theoccupant to his/her one shoulder has been proposed in addition to atwo-point type seat belt which holds the waist of the occupant.

Prior to specific explanations to the Related Art, a general and basicstructure of a three-point seat belt 70 capable of using a loop hangeraccording to the invention by referring to FIG. 3 which is a perspectiveview of an interior of an automobile 1, is explained. Incidentally, thetree-point seat belt 70 is provided at each of front seats and rearseats. However, an example of a seat belt system provided at a driver'sseat 2 will be explained below for simplification of explanation.

The tree-point type seat belt 70 is extended so as to reach three pointsof a first anchor 71 provided at a lower portion of a center pillar 3, asecond anchor 72 provided on a portion of a floor positioned between thedriver's seat 2 and a front passenger's seat 4, and a third anchor 73provided at an upper portion of the center pillar 3. The three-pointtype seat belt 70 comprises a webbing belt or a seat belt webbing S, oneend thereof being mounted to the first anchor 71 and the other end beingtaken up or retracted in a retractor (not shown), and a fixing belt 75,one end thereof being mounted to the second anchor 72 and the other endhaving a buckle device 77. Also, a tongue portion or plate 76 which islocked to the buckle device 77 is provided at an intermediate portion ofthe webbing belt S.

FIG. 1 is a perspective view of a conventional loop hanger for a seatbelt 100 mounted to the third anchor 73. The loop hanger for a seat belt100 is provided with a base member 80 which is made of a steel plate(metal) and which has a bolt passing-through hole 81 for mounting theloop hanger 100 to the third anchor 73 through a bolt and a base slot 82(refer to FIG. 2) through which the webbing belt S is moved in the loophanger 100 in a sliding manner, and the periphery of the base slot 82 ofthe base member 80 is entirely covered with a cover member 90 made ofsynthetic resin, which is insert-molded.

This cover member 90 covers an edge portion 82 a of the base slot 82 toform a slot 91 through which the webbing belt S is slidably moved alongthe edge portion 82 a of the base slot 82. That is, the webbing belt Sis turned back at a lower edge face portion of the slot 91 and it can bepulled out from/taken up in the retractor.

However, since the slot 91 is formed by covering the edge portion 82 aof the base slot 82 with the cover member 90 which is made of syntheticresin and which is insert-molded, the slidability of the webbing belt Sis apt to lower according to reduction of anti-gum up property.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above problem and anobject thereof is to provide a loop hanger for a seat belt which can bemaintained with the slidability of the webbing belt without influencedby reduction of anti-gum up property and which can reduce fractiondefective or reduce a occurrence ratio of inferior goods, and a methodfor manufacturing the same.

To achieve the object, according to a first aspect of the presentinvention, there is provided a loop hanger for a seat belt (10) whichslidably hangs a seat belt webbing (S), comprising a base member (20)made of a metal plate and having a slot (21) through which the seat beltwebbing (S) is moved, wherein the slot (21) is constituted with a longside portion (21 a) extending in a generally horizontal direction and apair of left and right short side portions (21 b) communicating withleft and right end portions of the long side portion (21 a) andextending downwardly, a portion of the base member (20) surrounded bythe long side portion (21 a) and the pair of short side portions (21 b)is curved smoothly from a side of the long side portion (21 a) in agenerally C-shaped sectional configuration, and a curved face (21 f)formed by curving the portion of the base member (20) serves as aportion (20 a) through which the seat belt webbing (S) is turned back.

Therefore, according to the first aspect of the present inventionstructured in the above manner, since the base member (20) is structuredsuch that at least the portion (20 a) through which the seat beltwebbing (S) is turned back is formed integrally with the base member(20) so as to curve smoothly in a generally C-shaped sectionalconfiguration, face pressure acting upon the seat belt webbing (S) canbe reduced, thereby improving durability of the seat belt webbing (S),and the thickness of the base member (20) can be reduced, therebyachieving weight-reduction and cost-reduction.

Also, since the base member (20) is made of a metal plate and theportion (20 a) through which the seat belt webbing (S) is turned back isformed in a curved face so as to curve smoothly in a generally C-shapedsectional configuration, the loop hanger for a seat belt can bemaintained with the slidability of the webbing belt without influencedby reduction of anti-gum up property.

According to a second aspect of the invention, there is provided a loophanger for a seat belt (10) which slidably hangs a seat belt webbing(S), comprising a base member (20) made of a metal plate and having aslot (21) through which the seat belt webbing (S) is moved; and a covermember (30) which covers a portion of the base member (20) other than atleast a portion (20 a) of the base member (20) through which the seatbelt webbing (S) is turned back, wherein the slot (21) of the basemember (20) is constituted with a long side portion (21 a) extending ina generally horizontal direction and a pair of left and right short sideportions (21 b) communicating with left and right end portions of thelong side portion (21 a) and extending downwardly, a portion of the basemember (20) surrounded by the long side portion (21 a) and the pair ofshort side portions (21 b) is curved smoothly from a side of the longside portion (21 a) in a generally C-shaped sectional configuration, anda curved face (21 f) formed by curving the portion of the base member(20) serves as a portion (20 a) through which the seat belt webbing (S)is turned back, and wherein the cover member (20) is provided so as tocover a portion of the base member (20) other than at least the portion(20 a) through which the seat belt webbing (S) is turned back and whichis formed in a generally C-shaped sectional configuration.

In addition to the above operation and effect, since the cover member(30) is formed so as to cover the portion of the base member (20) otherthan the portion (20 a) through which the seat belt webbing (S) isturned back, the seat belt webbing (S) directly slides on the metalplate-made portion (20 a) with the generally C-shaped sectionalconfiguration through which the seat belt webbing (S) is turned back, sothat the loop hanger for a seat belt can be maintained with theslidability of the webbing belt without influenced by reduction ofanti-gum up property.

According to a third aspect of the invention, there is provided a loophanger for a seat belt according to the first or second aspect, whereinthe center of curvature of the curved face (21 f) with the generallyC-shaped sectional configuration constituting the portion (20 a) throughwhich the seat belt webbing (S) is turned back is positioned on a sideof the center of the thickness of the base member (20).

Therefore, according to the third aspect of the invention, since thecenter of curvature of the curved face (21 f) with the generallyC-shaped sectional configuration constituting the portion (20 a) throughwhich the seat belt webbing (S) is turned back is positioned on the sideof the center of the thickness of the base member (20).

According to a fourth aspect of the invention, there is provided a loophanger for a seat belt according to any one of the first to thirdaspects, wherein, regarding the slot (21) of the basis member (20), acoarse surface portion (20 c) is formed on the portion (20 a) throughwhich the seat belt webbing (S) is turned back and which is formed inthe generally C-shaped sectional configuration.

Since the coarse surface portion (20 c) is formed on the metalplate-made portion (20 a) with the generally C-shaped sectionalconfiguration through which the seat belt webbing (S) is turned back,the seat belt webbing (S) slides on the coarse surface portion (20 c)directly.

According to a fifth aspect of the invention, there is provided a loophanger for a seat belt according to any one of the first to fourthaspects, wherein reinforcement ribs (R) are provided on both left andright sides of the slot (21) of the base member (20).

In the above construction according to the fifth aspect of theinvention, since the reinforcement ribs (R) are provided on both theleft and right sides of the slot (21) on the base member (20), bothportions of the base member (20) which are positioned on the both sidesof the slot (21) can be improved in strength. Accordingly, even when theseat belt webbing (S) is moved to one of the both sides and pressure ofthe webbing (S) is concentrated on the one, safety of the seat beltwebbing (S) can be improved.

According to a sixth aspect of the invention, there is provided a loophanger for a seat belt according to the fifth aspect, wherein thereinforcement ribs (R) are formed on the both left and right sides ofthe slot (21) of the base member (20) along an opening edge, and asectional configuration of each reinforcement rib has a generallysemi-circular sectional configuration projecting on one side surface ofthe base member (20).

According to the sixth aspect of the invention, since the reinforcementribs (R) are provided on the both edge sides of the slot (21) along theopening edge and each rib (R) projects on one side surface of the basemember (20) in a semi-circular or semi-spherical sectionalconfiguration, the seat belt webbing (S) can be rounded along adirection in which the seat belt webbing (S) is turned back so that theseat belt webbing (S) can be prevented from being injured.

According to a seventh aspect of the invention, there is provided a loophanger for a seat belt according to the fifth aspect, wherein thereinforcement ribs (R) are formed on the both left and right sides ofthe slot (21) of the base member (20) along an opening edge, and asectional configuration of each reinforcement rib has a generallycircular sectional configuration projecting on both side surfaces of thebase member (20).

Since each reinforcement rib (R) is provided on both side surfaces ofthe base member (20) so as to project in a circular or sphericalsectional configuration, the seat belt webbing (S) can be rounded alonga direction in which the seat belt webbing (S) is turned back so thatthe seat belt webbing (S) can be prevented from being injured and thestrength thereof can further be improved.

According to an eighth aspect of the invention, there is provided amethod for manufacturing a loop hanger for a seat belt (10) whichslidably hangs a seat belt webbing (S), wherein, after a slot (21) whichcomprises a long side portion (21 a) extending in a generally horizontaldirection and a pair of left and right short side portions (21 b)communicating with left and right end portions of the long side portion(21 a) and extending downwardly, and through which the seat belt webbing(S) is moved is pierced in a material member made of a metal plate toform a base member (20) made of the metal plate, a portion of the basemember (20) which is surrounded by the long side portion (21 a) and thepair of left and right short side portions (21 b) is curved smoothlyfrom the long side portion (21 a) side in a generally C-shaped sectionalconfiguration to form a curved face (21 f) and a portion (20 a) throughwhich the seat belt webbing (S) is turned back is formed by the curvedface (21 f); and the center of curvature of the curved face (21 f)constituting the portion (20 a) through which the seat belt webbing (s)is turned back is moved to a side of the center of the thickness of thebase member (20).

According to a ninth aspect of the invention, there is provided a methodfor manufacturing a loop hanger for a seat belt (10) which slidablyhangs a seat belt webbing (S), wherein, after a slot (21) whichcomprises a long side portion (21 a) extending in a generally horizontaldirection and a pair of left and right short side portions (21 b)communicating with left and right end portions of the long side portion(21 a) and extending downwardly, and through which the seat belt webbing(S) is moved is pierced in a material member made of a metal plate toform a base member (20) made of the metal plate, a portion of the basemember (20) which is surrounded by the long side portion (21 a) and thepair of left and right short side portions (21 b) is curved smoothlyfrom the long side portion (21 a) in a generally C-shaped sectionalconfiguration to form a curved face (21 f) and a portion (20 a) throughwhich the seat belt webbing (S) is turned back is formed by the curvedface (21 f); the center of curvature of the curved face (21 f)constituting the portion (20 a) through which the seat belt webbing (S)is turned back is moved to a side of the center of the thickness of thebase member (20) to form the base member (20) which is provided with theportion (20 a) through which the seat belt webbing (S) is turned back;and a cover member (30) is provided so as to cover a portion of the basemember (20) other than at least the portion (20 a) through which theseat belt webbing (S) is turned back.

According to a tenth aspect of the invention, there is provided a methodfor manufacturing a loop hanger for a seat belt (10) which slidablyhangs a seat belt webbing (S), wherein, after a slot (21) whichcomprises a long side portion (21 a) extending in a generally horizontaldirection and a pair of left and right short side portions (21 b)communicating with left and right end portions of the long side portion(21 a) and extending downwardly, and through which the seat belt webbing(S) is moved is pierced in a material member made of a metal plate toform a base member (20) made of the metal plate, the center of curvatureof a curved face (21 f) to be formed in the next step is moved to a sideof the center of the thickness of the base member (20) in advance; and aportion of the base member (20) which is surrounded by the long sideportion (21 a) and the pair of left and right short side portions (21 b)is curved smoothly from the long side portion (21 a) in a generallyC-shaped sectional configuration to form a curved face (21 f) and aportion (20 a) through which the seat belt webbing (S) is turned back isformed by the curved face (21 f).

According to an eleventh aspect of the invention, there is provided amethod for manufacturing a loop hanger for a seat belt (10) whichslidably hangs a seat belt webbing (S), wherein, after a slot (21)comprising a long side portion (21 a) extending in a generallyhorizontal direction and a pair of left and right short side portions(21 b) communicating with left and right end portions of the long sideportion (21 a) and extending downwardly is formed in material made of ametal plate to form a base member (20) made of the metal plate, thecenter of curvature of a curved face (21 f) to be formed in the nextstep is moved to a side of the center of the thickness of the basemember (20) in advance; a portion of the base member (20) which issurrounded by the long side portion (21 a) and the pair of left andright short side portions (21 b) is curved smoothly from the long sideportion (21 a) in a generally C-shaped sectional configuration to form acurved face (21 f) and a portion (20 a) through which the seat beltwebbing (S) is turned back is formed by the curved face (21 f); and acover member (30) is provided so as to cover a portion of the basemember (20) other than at least the portion (20 a) through which theseat belt webbing (S) is turned back.

According to each of the eighth to eleventh aspects of the invention,since the portion (20 a) through which the seat belt webbing (S) isturned back is formed in a curved face having a large radius ofcurvature such that the seat belt webbing (S) is smoothly curved, theface pressure acting upon the seat belt webbing (S) can be made small,so that the durability of the seat belt webbing (S) can be improved andthe thickness of the base member (20) can be reduced, thereby decreasingweight and manufacturing cost.

Also, since the base member (20) is made of a metal plate and theportion (20 a) through which the seat belt webbing (S) is turned back isformed in a curved face so as to curve smoothly in the generallyC-shaped sectional configuration, the loop hanger for a seat belt can bemaintained with the slidability of the webbing belt without influencedby reduction of anti-gum up property.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and further objects and novel features of the presentinvention will more fully appear from the following detailed descriptionwhen the same is read in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view showing a loop hanger for a three pointtype seat belt in a conventional art;

FIG. 2 is a sectional view taken along arrow II—II in FIG. 1;

FIG. 3 is a perspective view for explaining an entire structure of athree point type seat belt;

FIG. 4 is a perspective explanatory view of a loop hanger for a seatbelt according to a first embodiment of the present invention;

FIG. 5 is a perspective explanatory view of a loop hanger for a seatbelt according to a second embodiment of the present invention;

FIG. 6 is a perspective explanatory view showing a piercing and trimmingstep of steps for manufacturing a relatively small number of basemembers 20 made of a metal plate;

FIG. 7 is a perspective explanatory view showing a piercing step of themanufacturing steps;

FIG. 8 is a perspective explanatory view showing a chamfering step ofthe manufacturing steps;

FIG. 9 is a perspective explanatory view showing a squeezing step of themanufacturing steps;

FIG. 10 is a perspective explanatory view showing a first curved faceforming step of the manufacturing steps;

FIG. 11 is a perspective explanatory back view showing the first curvedface forming step of the manufacturing steps;

FIG. 12 is a perspective explanatory view showing a second curved faceforming step of the manufacturing steps;

FIG. 13 is a perspective explanatory back view showing the second curvedface forming step of the manufacturing steps;

FIG. 14 is a perspective explanatory view showing a center of curvaturemoving step for moving the center of curvature of the manufacturingsteps;

FIG. 15 is a perspective explanatory back view showing the center ofcurvature moving step of the manufacturing steps;

FIG. 16 is a perspective explanatory view showing a trimming and cuttingstep of the manufacturing steps;

FIG. 17 is a perspective explanatory back view showing the trimming andcutting step of the manufacturing steps;

FIG. 18 is a perspective explanatory view showing a bending step of themanufacturing steps;

FIG. 19 is a perspective explanatory back view showing the bending stepof the manufacturing steps;

FIG. 20 is a perspective explanatory view showing a process ofmanufacturing many base members which are made of a metal plate;

FIG. 21A is an explanatory sectional view showing a first stage of acurved face forming step;

FIG. 21B is an explanatory sectional view showing a second stage of acurved face forming step;

FIG. 21C is an explanatory sectional view showing a third stage of acurved face forming step;

FIG. 21D is an explanatory sectional view showing a fourth stage of acurved face forming step;

FIG. 22 is an explanatory sectional view showing a step for moving thecenter of curvature; and

FIG. 23 is an explanatory sectional view showing a step a bending step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained below withreference to the accompanying drawings. Like members are designated bylike reference characters.

As shown in FIG. 4, a loop hanger for a seat belt 10 illustrated as afirst embodiment is to hang a seat belt webbing S slidably and it can bemounted with a cover member (not shown) attachably/detachablystructured, as necessary. The loop hanger 10 can be constituted with abase member 20 made of a metal plate and having a slot 21, which isprovided with a portion 20 a which is formed in a generally C-shapedsectional configuration and through which the seat belt webbing S isturned back.

As shown in FIG. 5, a loop hanger for a seat belt 10 illustrated as asecond embodiment is constituted with a base member 20 made of a metalplate and having a slot 21, which is provided with a portion 20 a whichis formed in a generally C-shaped sectional configuration and throughwhich the seat belt webbing S is turned back, and a cover member 30which covers a portion of the base member 20 other than at least theportion 20 a which is formed in a generally C-shaped sectionalconfiguration and through which the seat belt webbing S is turned back.

The structure of the base member 20 which is made of a metal plate andwhich has the same structure common to the first and second embodimentsmentioned above.

In these embodiments, the base member 20 is formed by punching a hightensile steel blank having the thickness of about 3 mm to conduct pressworking on the punched blank, and it comprises a mounting portion 20Aand a seat belt holding portion 20B, as shown in FIGS. 4 and 5. Themounting portion 20A is provided with a mounting hole 22 applied formounting the loop hanger for a seat belt 10 to a center pillar 3 of avehicle body, and the seat belt holding portion 20B is provided with aslot 21 through which the seat belt webbing S is slidably moved, asmentioned above.

As shown in FIG. 7, the slot 21 is constituted with a long side portion21 a extending in a generally horizontal direction and a pair of shortside portions 21 b which communicate with left and right end portions ofthe long side portion 21 a and extend downwardly. Referring back toFIGS. 4 and 5, a portion (denoted as numeral “21 f”) of the base member20 which is surrounded by the long side portion 21 a and the short sideportions 21 b is curved in smoothly a generally C-shaped sectionalconfiguration from the side of the long side portion 21 a, therebyforming the curved face 21 f serving as the portion 20 a through whichthe seat belt webbing S is slidingly turned back. Furthermore, thecenter of curvature of the curved face 21 f with the generally C-shapedsectional configuration which constitutes the portion 20 a through whichthe seat belt webbing S is turned back is positioned at the center sideof the thickness of the base member 20 in a direction of thickness ofthe base member 20. Furthermore, a coarse surface portion 20 c (as shownin FIGS. 18 and 19 as plurality of dots) is formed on the portion 20 athrough which the seat belt webbing S is turned back.

Also, reinforcement ribs R (shown in FIGS. 22 and 23) are provided onthe base member 20 on both left and right sides of the slot 21. Thereinforcement ribs R are formed on the both left and right sides of theslot 21 along the opening edge thereof, and the ribs R are provided onone side surface of the base member 20 so as to project in asemi-spherical or semi-circular sectional configuration. Alternatively,the ribs R may be provided so as to project on both side surfaces in agenerally spherical or circular sectional configuration.

Next, methods for manufacturing the base members 20 made of a metalplate which have been explained in the first and second embodiments willbe explained. A method for manufacturing a relatively small number ofbase members 20 made of a metal plate will first be explained withreference to FIGS. 6 to 19.

The method comprises the following steps in combination.

A piercing and trimming step for cutting off a material member made of ametal plate to a development state of the base member 20 having a clampportion C by trimming, and for piercing a mounting hole 22 for mountingon a vehicle body side (refer to FIG. 6);

a piercing step for piercing the pierced and trimmed material member toform a slot 21 comprising the long side portion 21 a extending in agenerally horizontal direction and the pair of left and right short sideportions 21 b which communicate with both the left and right end of thelong side portion 21 a to extend downwardly (refer to FIG. 7);

a chamfering step (or stamping step) for chamfering a periphery of theslot 21 (refer to FIG. 8);

a squeezing step (or coining step) for squeezing (or coining) aperiphery of the portion 20 a through which the seat belt webbing S isturned back and which is constituted with a portion surrounded by thelong side portion 21 a and the pair of left and right short sides 21 bso that the squeezed portion F is made lower than the surface of thebase member 20 (refer to FIG. 9);

a first curved face forming step for pressing a free end portion of theportion 20 a through which the seat belt webbing S is turned back, whichis surrounded by the squeezed portion F formed in the squeezing step,towards a back surface to form the curved face 21 f (refer to FIGS. 10and 11);

a second curved face forming step for further pressing the curved face21 f which has been curved in the first curved face forming step tocurve it further (refer to FIGS. 12 and 13);

a center of curvature moving step for moving the center of curvature ofthe curved face 21 f which has been formed in the first and secondcurved face forming steps to the center of the thickness of the basemember 20 by bending lower portions 21 m, 21 p, 21 n and 21 q of thebase member 20 (refer to FIGS. 14 and 15);

a trimming and cutting step for trimming and cutting the clamp portion Cwhich has been applied for clamping to a final shape of the base member20 after the center of curvature moving step of the curved face 21 f(refer to FIGS. 16 and 17); and

a bending step for bending the base member 20 which has been trimmed andcut to the final shape in the trimming and cutting step to apredetermined angle (refer to FIGS. 18 and 19).

Then, a first method applied to a case where a large number of basemembers 20 made of a metal plate are manufactured will be explained withreference to FIG. 20.

The first method comprises the following steps in combination:

a piercing step for piercing a pilot hole p and a slot 21 on a materialblank made of a metal plate, the slot 21 comprising a long side portion21 a extending in a generally horizontal direction and a pair of leftand right short side portions 21 b which communicate with both ends ofthe long side portion 21 a to extend downwardly (refer to “a” in FIG.20);

a trimming and cutting step for trimming and cutting the piercedmaterial blank to a development state of the base member 20 while aconnecting strip portion B for forward feeding (refer to “b1 and “b2” inFIG. 20);

a chamfering step for chambering a periphery of the slot 21 (refer to“c” in FIG. 20);

a squeezing step for squeezing a periphery of the portion 20 a throughwhich the seat belt webbing S is turned back and which is constitutedwith a portion surrounded by the long side portion 21 a and the pair ofleft and right short sides 21 b so that the squeezed portion F is madelower than the surface of the base member 20 (refer to “d” in FIG. 20):

a curved face forming step for pressing the portion 20 a through whichthe seat belt webbing S is turned back and which includes the squeezedportion F which has been achieved in the squeezing step sequentially ina stepped manner from the long side portion 21 a side to form a curvedface 21 f bent smoothly in a generally C-shaped sectional configuration(refer to “e1” to “e4” in FIG. 20);

a center of curvature moving step for moving the center of curvature ofthe curved face 21 f which has been formed in the curved face formingstep towards the center side of the thickness of the base member 20(refer to “f” in FIG. 20);

a burring step for forming a burring portion towards a back face of thebase member 20 in order to form reinforcement ribs R on both left andright sides of the slot 21 (refer to “g” in FIG. 20);

a forming step for forming the burring portion which has been formed inthe burring step in a semi-circular sectional configuration (refer to“h” in FIG. 20);

a bending step for bending the base member 20 to a generally L-shapedsectional configuration via an upper edge portion of the slot 21 of thebase member 20 (refer to “i” in FIG. 20);

a mounting hole piercing step for piercing a mounting hole 22 for a loophanger for a seat belt 10 at a center of the pilot hole P for forwardfeeding which has been pierced in the piercing step (refer to “j” inFIG. 20); and

a cutting step for cutting the connecting strip portion B for forwardfeeding (refer to “k” in FIG. 20).

Next, a second method applied to a case where a large number of basemembers 20 made of a metal plate are manufactured will be explainedbriefly.

In the above first method, subsequent to the curved face forming stepfor forming the curved face 21 f, the center of curvature moving stepfor moving the center of curvature of the curved face 21 f which hasbeen formed in the curved face forming step has been performed. In thesecond method, however, the center of curvature moving step is performedbefore the curved face 21 f is formed in the curved face forming step.

That is, the center of curvature moving step is performed on the portion20 a through which the seat belt webbing S is turned back and whichincludes a portion surrounded by the portion F which has been squeezedin the squeezing step in advance such that the center of curvature ofthe curved face 21 f to be formed in the next step is moved towards thecenter of the thickness of the base member 20.

In addition, in the center of curvature moving step, the center ofcurvature is moved towards the center of the thickness of the basemember 20, and simultaneously the free end portion of the portion 20 athrough which the seat belt webbing S is turned back and which includesa portion surrounded by the portion F which has been squeezed in thesqueezing step is slightly bent in a direction in which it is bent inthe curved face forming step performed as the next step, so that forminga curved face which is performed in the next step is facilitated.

Furthermore, in the second method, a curved face is formed bysequentially performing eight stages of the first to eighth curved faceforming steps. Thereby, a smooth curved face 21 f, reduction of burdenon respective dies, size reduction of a pressing device to be used canbe achieved.

In the respective steps of the manufacturing method, the curved faceforming step for forming the curved face 21 f on the portion 20 athrough which the seat belt webbing S is turned back is completed bysequentially performing four stages of the first curved face formingstep to the fourth curved face forming step in the first method, asshown in “e1”, “e2”, “e3”, and “e4” in FIG. 20, or FIGS. 21A to 21D,while the curved face forming step is completed by sequentiallyperforming eight stages of the first curved face forming step to theeighth curved face forming step in the second method. Thereby, a smoothcurved face 21 f, reduction of burden on respective dies, size reductionof a pressing device to be used can be achieved. Incidentally, thecurved face forming step can include two or three stages, or nine ormore stages.

Also, it is very important that in the first method, the portion 20 a isslightly bent from the long side portion 21 a side, thereby obtaining astarting point for forming the curved face 21 f in the first curved faceforming step, as shown in FIGS. 21A to 21D, while in the second method,the free end portion of the portion 20 a through which the seat beltwebbing S is turned back is bent slightly in a direction of bendingperformed in next the curved face forming step, thereby obtaining astarting point for forming the curved face 21 f. Therefore, a smooth orbeautiful curved face 21 f can easily be achieved in the next andsubsequent steps.

This curved face 21 f is curved so as to slidably contact with the seatbelt webbing S in an angle range of 120 to 180°. In view of improvementto maintain with slidability of the webbing belt without to beinfluenced by reduction of anti-gum up property, it is preferable thatthe curved face 21 f contacts with the seat belt webbing S in an anglerange of 130 to 150°.

Furthermore, since the center of curvature of the curved face 21 f whichhas been formed in the above-mentioned curved face forming step is movedtowards the center of the thickness of the base member 20 in the centerof curvature moving step, the slidability of the webbing belt can beimproved largely.

As mentioned above, the reinforcement ribs R are provided on the leftand right sides of the slot 21 in the base member 20 along the openingedge of the slot by the burring step and the forming step. Particularly,in this embodiment, each rib R is formed so as to project on one sidesurface of the base member 20 in a generally semi-spherical orsemi-circular sectional configuration. Each rib may be provided so as toproject on both side surfaces of the base member 10 in a generallyspherical or circular sectional configuration, as necessary.

As mentioned above, the base member 20 is bent from the top portion ofthe slot 21 in a generally L-shape as viewed from a side by the bendingstep. The bending may be performed in a direction opposed to thedirection of the free end portion of the curved face 21 f, as thepresent embodiment, but it may be performed in the same direction as thefree end portion of the curved face 21 f.

Also, since the periphery of the slot 21 comprising the long sideportion 21 a extending in a generally horizontal direction and the pairof short side portions 21 b communicating with both the left and rightends of the long side portion 21 a to extend downwardly is chamfered inthe chamfering step, stress concentrated due to the edge of theperiphery can be prevented from acting on the cover member, therebypreventing resin of the cover member from being broken.

Furthermore, since the peripheral portion of the portion 20 a throughwhich the seat belt webbing S is turned back, which has been formed inthe piercing step is squeezed in the squeezing step so that the squeezedportion F is made lower than the surface of the base member 20, the seatbelt webbing S can be prevented from riding on the covered resinportion, so that the slidability of the webbing belt can be improvedlargely, in other wards, the slidability of loop hanger with the webbingbelt can be improved largely.

The entire contents of Japanese Patent Application P2000-398696 (filedon Dec. 27, 2000) and P2000-199851 (filed on Jun. 30, 2000) areincorporated herein by reference.

Although the invention has been described above by reference to certainembodiments of the invention, the invention is not limited to theembodiments described above. Modifications and variations of theembodiments described above will occur to those skilled in the art, inlight of the above teachings. The scope of the invention is defined withreference to the following claims.

1. A loop hanger for a seat belt through which a seat belt may slidablypass, the loop hanger comprising: a base member (20) having a slot (21)through which a belt may pass wherein the base member (20) is made of ametal plate; and a tongue (20 a) formed integrally with the base member(20) wherein the tongue is substantially arcuate, wherein a center ofarc of the arcuate tongue (20 a) lies within a plane of the base member;wherein the belt is slidably turned back on the arcuate tongue (20 a);wherein a half portion of the arcuate tongue (20 a) is located so as tobe protruded from one surface side of the plane of the base member (20);wherein another half portion of the arcuate tongue (20 a) is located soas to be protruded from the other surface side of the plane of the basemember (20); and wherein both of the half portion and the other halfportion of the arcuate tongue are unitarily formed from the metal platewhich forms the base member.
 2. A loop hanger for a seat belt (10)according to claim 1, further comprising: a cover member (30) whichcovers a portion of the base member (20) other than at least a portionof the base member (20) through which the seat belt is turned back.
 3. Aloop hanger for a seat belt (10) according to claim 1, wherein a coarsesurface portion (20 c) is formed on the portion (20 a) through which theseat belt is turned back.
 4. A loop hanger for a seat belt (10) throughwhich a seat belt may slidably pass, the loop hanger comprising: a basemember (20) having a slot (21) through which a belt may pass wherein thebase member (20) is made of a metal plate; and a tongue (20 a) formedintegrally with the base member (20) so that the tongue is also made ofthe metal plate (20) wherein the tongue is substantially arcuate,wherein a center of arc of the arcuate tongue (20 a) lies within a planeof the base member; wherein the belt is slidably turned back on thearcuate tongue (20 a); wherein a half portion of the arcuate tongue (20a) is located so as to be protruded from one surface side of the planeof the base member (20); wherein another half portion of the arcuatetongue (20 a) is located so as to be protruded from the other surfaceside of the plane of the base member; and wherein reinforcement ribs (R)are provided on both left and right sides of the slot (21) of the basemember (20).
 5. A loop hanger for a seat belt according to claim 4,wherein the reinforcement ribs (R) are formed on the both left and rightsides of the slot (21) of the base member (20) along an opening edge;and wherein a sectional configuration of each reinforcement rib has agenerally semi-circular sectional configuration projecting on one sidesurface of the base member (20).
 6. A loop hanger for a seat beltaccording to claim 4, wherein the reinforcement ribs (R) are formed onthe both left and right sides of the slot (21) of the base member (20)along an opening edge; and wherein a sectional configuration of eachreinforcement rib has a generally circular sectional configurationprojecting on both side surfaces of the base member (20).